Subsea electrical connectors for use underwater are known, and are for example described in the document GB 2 192 316 A. A first connector part of the subsea electrical connector has at least one pin projecting from a support which is inserted into a housing and fixed in place by a retainer ring. The pin has an axially extending conductive core, for example a copper core, which is surrounded by an insulating sleeve which is arranged to expose an area of the conductive core at or near the tip of the pin for making electrical contact with a contact socket in the second connector part of the subsea electrical connector.
In the de-mated condition of the first and second connector parts, the pin may be exposed to the external environment and thus for example to seawater when deployed subsea. The insulating sleeve is intended to insulate the conductive core of the pin from exposure to the external environment and to provide electrical insulation. In the mated condition of the first and second connector parts, a portion of the pin and thus the insulating sleeve can still be exposed to surrounding seawater. Since such electrical subsea connectors can have a lifetime of more than 25 years, the insulation of the conductive core can experience long term subsea exposure. Electrophoresis may lead to an intrusion of seawater into the insulation. Furthermore, when such subsea connector is used for high voltage applications, high electrical stresses can occur in proximity to the pin of the connector, which can lead to a degradation of the material exposed to such high electrical field stresses, and may finally lead to a failure of such material, for example to the failure of a seal.
To overcome these difficulties, it is proposed in the patent U.S. Pat. No. 7,794,254 B2 to make use of a metal or metalized coating formed on the outer surface of an insulating sleeve. The metal or metalized coating can suppress penetration of water into the insulating sleeve and further can reduce localized condensing of equipotential electric field lines whereby electrical stresses can be reduced.
Furthermore, the document with the application number PCT/EP2014/065278 discloses the use of a ceramic coating on a component of a subsea connector to improve the corrosion resistance.
In certain configurations of wet-mateable connectors, it is desirable to provide a seal towards the connector pin when the connector parts are mated. The coating of the pin may require an adaptation of such seal to accommodate the coating, which makes the connector design more difficult. Further, at the transition between the non-coated surface and the coated surface on the pin, sliding of the seal over the pin may be hampered and retaining of a liquid-tight seal during such sliding may be more difficult. At the transition between the non-coated surface and the coated surface on the pin, electrical stresses might furthermore be difficult to control. Also, it might be necessary to manufacture such coating with quite high precision, resulting in a complex manufacturing process.
It is desirable to improve the mating of subsea connectors, in particular in a subsea environment, and to make subsea connectors more reliable and extend their lifetime. In particular, it is desirable to avoid negative effects of electrical stresses. Also, it is desirable to facilitate the manufacturing of a subsea connector and to make it more cost efficient.